Starting device for internal combustion engines



A. CALLSEN Aug. 25, 1936.

STARTING DEVICE FOR INTERNAL COMBUSTION :ENGINES Original Filed April18, 1932 2 Sheets-Sheet 1 A. CALLSEN Aug. 25, 1936.

STARTING DEVICE FOR INTERNAL COMBUSTION ENGINES Original Filed April.18, 1932 2 Shets-Sheet 2 I Ill/Ill Patented Aug. 25, 1936 PATENT orrce- STARTING DEVICE FOR INTERNAL COMBUSTION ENGINES Albert Callsen,Stuttgart, Germany, assignor to Robert Bosch Aktiengesellschaft,Stuttgart,

Germany Original application April 18, 1932, Serial No. 606,006. Dividedand this application March 26, 1935, Serial No. 13,169. In Germany April12 Claims. (Cl. 290-38) The present invention relates to a startingdevice for internal combustion engines, in which an electric motor isemployed and preferably also an inertia mass which is brought to a highspeed of rotation by means of the electric motor, and

then coupled to the internal combustion engine to be started, and inwhich a friction clutch is introduced into the driving connection to thepinion engaging in the rim of the flywheel of the engine.

This application is a division of my applica tion Ser. No. 606,006,filed April 18, 1932.

In a known arrangement the pinion is permanently connected with theinertia mass so as to transmit power through a. spring-loadedplateclutch.

This construction has the disadvantage that each time on the engagementof the pinion in the toothed rim of the flywheel oi the motor the pinionas well as the toothed-rim of the flywheel are strongly worn and evenare often damaged. It is also already known in electric starters whichhave no separate inertia mass to make the plate-clutch inserted betweenthe pinion and the armature of the starting motor capable oftransmitting power by a pressure member which can screw axially on thedriving shaft. In this case the clutch only establishes the powerconnection when the pinion on coming into engagement, is prevented fromfreely rotating. In order however, that the pinion may fully engage, itmust become engaged by an auxiliary force before the transmission of themain torque, since an immediate engagement under full load would not bepossible because the flank pressure of the teeth is so great from thefirst moment of the engagement that the axial attractive force of thearmature does not suflice to entirely push in the pinion. This secondconstruction is thus not at all possible for flywheel starters-becausein these the full torque is present immediately upon engagement. V

According to the present invention the drawback of the first-mentionedconstruction is removed, whilst the starting device of the secondnamedconstruction is also made applicable to flywheel starters in that thepower connection between the pinion and the inertia mass, which isefiected by a plate-clutch operated by an axially screwing pressuremember, is capable of being initiated at will.

An example of construction of a starter according to the invention isshown in the accom-.

pcnying' drawings, in which:-

1 is a semi-diagrammatic sectional view of a starter having an axiallyadjustable armature, in the position of rest,

Figure 2 is a plan of connections of the starting device,

Figure 3 shows the starter in engagement, but with the plate-clutch outof engagement, and

Figure 4 shows the starter in the working position.

In Figures 1, 3 and i, l is the armature of an electric starting motorwhich in known manner can be axially displacedvby the magnetic force ofthe field winding. n the armature shaft 2 is keyed a flywheel 3 and apinion 4 is revolubly mounted on the shaft 2. The pinion 4 has a shank 5which has an external thread 6 of quick pitch. A nut i can move on theshank by means of the thread 6. The torque of the armature l istransmitted to the pinion 4 through a plateclutch 6. The plates 9 of theclutch engage by means of projections ID in recesses H in the flange itof the flywheel 3, whilst the plates i3 engage by projections M ingrooves l5 in the nut i. A. spring ii is tensioned between the nut l anda stop i6 on the shank 5 of the pinion, and the spring tends to push thenut '1 against the plates.

In an opening of the casing l8 a lever 19 is pivotally mounted above theplate-clutch 8. One end of the lever projects into the casing, and

strikes against a flange 2! on the nut i when the lever is rocked, anddisplaces this latter on the shank 5.- The lever ,is pulled back by aspring 24 into its position of rest. Further, a switch 22 is so arrangedon the casing l8, that the switch arm is brought into the switched onposition by a finger 23 on the lever l9 when the lever is rocked. Theswitch arm carries a contact 26, opposite to which a contact 21 isfastened in an insulated manner on the casing. The switch arm 25 is heldin its on position by a holding coil 28 and is raised by a spring 29 assoon as the holding coil is deprived of current.

In the diagram of connections, Fig. 2, 30 is a 0 battery, one pole ofwhich is connected to earth and the other pole to a brush 34 of thestarting armature I. To the other brush 35 is connected one end of anauxiliary field winding 3! and one end of the holding coil 28 of theswitch 22 as well as one end of the main field winding 33. The two otherends of the windings 28 and 3| are connected to one pole of the switch32, the other pole of which is earthed. The second end of the winding 33is connected to the insulated contact 21 which lies-opposite the contact26 on the switch arm 26 connected to earth.

The mode of operation of the starting device is as follows:.- A

In order to start the internal combustion englue, the switch 32 isclosed, thus closing the circuit through the auxiliary field winding 35.It is plain from Fig. 2 that the holding coil 28 in parallel with theauxiliary field winding is also excited by the closing of the switch 32,but as that coil is unable to close the switch 22 which controls thecircuit through the main field winding of the ,motor, the closing of theswitch 32 brings the auxiliary field Winding only into operation. Theresult'of this is, first, that the, armature l is axially displaced inknown manner by themagnetic force of the auxiliary field winding 3! andset in .slow, rotation. At this time the clutch is sufiiciently engaged,that is, there is a sufiicient frictional clutch connection between thearmature i and the pinion #3, by way of the pressure of the nut iagainst the clutch plates under the tension of thespring H and theengagement between the nut and the shank of the pinion, to cause thepinion topartake of the slow 'rotation of the armature and to be carriedalong with it until the pinion engages in the toothed rim 36 of theengine fiy'wheel.

As soon as the pinion is in engagement and is prevented by the rim ofthe flywheel 36 from further rotation, the nut l, which is sufiicientlyengaged with the clutch plates by the pressure of spring I! to continuein rotation, first screws itself along the shank of the pinion furthertoward the plates in consequence of the threaded connection between thenut and the shank of the 'pinion and their relative rotary movement andthereby puts the pinion. I

The torque of the starting motor is however too small in this first,switch position to turn over the engine and the motor stops. The leveri9 is now moved into the position shown in Fig. 3. On rocking the lever,the nut 'i is moved away from the clutch plates towards the stop itagainst the tension of spring H and thereby the clutch released. At thesame time the switch arm 25 is pressed by the finger 23 against thecontact 21. The working current circuit is thus now out in, since themain field winding is' also earthed through the switch 22. The startingmotor now runs idly with the inertia mass at a high speed and a serieswound motor attains of course a very high speed. Inorder to re-engagethe clutch 8, the lever is is moved back into its starting posiclutchinto operation on the tion. The spring H again pushes the nut i towardsthe plates and thus initiates the driving connection between thearmature i and flywheel 3 on the one hand and the hand.

The nut i now presses the plates together with a force which correspondsto the torque required on the pinion or, what amounts to the same pinionti on the other v thing, in accordance with the load imposed on theinertia mass in turning over the engine. The working current circuit ofthe starting'motor remains closed by the holding coil 28 so that thestarting motor can further assist the action of the flywheel 3. When thespeed of the starter on starting the engine is exceeded by the speed ofthe. engine, the pinion comes out of engagement in known manner.

In the above-described mode of operating the starting device. it is tobe noted that the succession of operations are the advancement of thepinion into engagement with the toothed rim of the flywheel bydisplacement of the armatureupon closure of the switch a: of theauxiliary winding, then disconnecting the pinion from the inertia massand setting the latter into full speed rotation by movement of the leverI 9 to throw out the the connected inertia mass are in slow rotation dueto the initial excitation oi the auxiliary field winding only.

However the pinion can also be put in engagement by the lever i9 insteadof with the aid of the displaceable armature, the nut l and the shank ofthe pinion being so formed that the nut can again. screw itself backtowards the clutch to a distance corresponding to the displacement forengaging the pinion, in order to make the clutch operative.

This makes it possible to effect the engagement of the pinion with thetoothed rim of the engine fiywheel after the inertia mass has been setin and while it is still in full speed rotation and without damage toeither the pinion or the engine flywheel, for at the moment when thepinion is moved by the lever toward the engaging position of the pinionwith the engine flywheel the clutch becomes disengaged and theconnection between the pinion and the rapidly rotating inertia mass isthereby broken and remains so as long as the lever is pressed againstthe nut. After the pinion is thus engaged with the toothed rim of theengine flywheel, the lever i9 is moved back to its neutral position andthis movement of the lever, of course, relieves thenut d from thepressure of the lever against it, whereupon the spring it again pushesthe nut towards the'clutch plates and thus initiates the drivingconnection between the rapidly rotating inertia mass and the pinion toturn over the engine through the established engagement of the pinionwith the toothed rim of the engine flywheel.

In carrying out the last-described method of starting by the device withthe electric motor and circuit arrangements shown in the drawings; thefirst operationstep of setting the inertia mass in full speed rotationbefore the pinion is engaged with the engine flywheel may be performedby leaving the switch 32 for the auxiliary field winding of the motoropen so as to avoid that displacement of the armature which would ad-Vance the pinion into engagement with the engine flywheel before theinertia mass has been spceded up, and manually closing the switch 22 forthe main field winding as may be required to set the armature and theconnected inertia mass into full speed rotation. I

A further advantage of the starting device ac.-

cording to the invention consists in that the use tor, a pinion freelymounted on the shaft of the armature, said pinionhaving a shank, a nutmounted to rotate on the shank of said pinion, a

plate-clutch between said pinion and said inertia mass controlled bysaid nut and means to displace said nnt. relatively to said pinion tooperate said clutch at will.

engines comprising an electric motor having a rotor and shafttherefor,an inertia. mass secured to the rotor of said motor, a pinion freelymounted on the shaft of the rotor, a sleeve secured to said pinion, anexternal thread'on said sleeve, a nut engaging said external thread, aplateclutch connecting said pinion and said inertia. mass and controlledby said nut, a spring urging said nut to engage said plate-clutch, and alever operable at will to displace said nut to disengage said clutch.

3. A starting device for internal combustion engines comprising anelectric motor having a rotor and a shaft therefor extending beyond saidrotor, an inertia mass secured to the rotor of said motor, a pinionfreely mounted on the shaft of the rotor, a sleeve secured to saidpinion, an

external thread on said sleeve, a nut engaging said external thred, aplate-clutch connecting said pinion and said inertiamass and controlledby said nut, a spring urging said nut to engage said plate clutch, alever operable at will to displace said nut to disengage said clutch andmeans to close-the power circuit of said motor upon operation ofsaid'lever.

4. A starting device for internal combustion engines comprising anelectric motor having a rotor and a shaft therefor extending beyond saidrotor, a power circuit for said motor, an inertia mass secured to therotor of said motor, a pinion freely mounted on the shaft of the rotor,a sleeve secured to said pinion, an external thread on said sleeve, ,anut engaging said external thread,

a plate-clutch connecting said pinion and said inertia mass andcontrolled by said nut, a spring -urging said nut toengage saidplate-clutch, a

lever operable at will to displace said nut to disengage said clutch, aswitch to close the power circuit of said motor upon operation of saidlever and means to hold the said switch in the closed position.

5. A starter for internal combustion engines comprising an electricmotor having an axially displaceable rotor and shaft, a main powercircuit, an auxiliary field circuit adapted to axially displace therotor of said motor and connected in parallel with the main powercircuit, a switch in the main power circuit, a holding coil for saidswitch, an inertia mass secured to the rotor of said motor, a pinionfreely mounted on the shaft of said rotor, a, nut mounted on saidpinion, a

plate-clutch operated by said nut and connecting said pinion with saidinertia mass, and a lever operable at will to disengage said clutch andto close said switch upon operation.

6. A starting device for an internal combustion engine comprising thecombination, with an internal combustion engine having a gear adapted tobe driven to turn over said engine, oi an electric motor having anaxially movable armature, a shaft axially movable with said armature, an

auxiliary field winding adapted upon excitationto impart axial movementto said armature and to rotate the same at relatively low speed, a pinion rotatably mounted on said shaft out of errgagement with said enginegear in one position of said armature and shaft but movable upon saidaxial movement of said armature and shaft to engagement with said enginegear, a main field winding for said motor adapted on excitation toimpart high speed rotation to said armature, an inertia mass mounted forrotation with said armature, a clutch-controlled driving connectionbetween said inertia member and said pinion, a

a displaceable rotary driving member out ofengagement with the engine inthe non-starting position, means to shift said driving member into saidengagement to start the engine, a friction plate clutch between saiddriving member and said inertia mass, means comprising a control memberautomatically movable in dependency on the position of said drivingmember to control said clutch and manually operable means to displacesaid control member to operate said clutch at will.

8. A starting device for an internal combustion engine comprising anelectric motor, a displaceable driving member out of engagement with theengine in the non-starting position and bodily movable into saidengagement to start the engine, means for driving said member from saidmotor including a multiple-part clutch automatically operating toestablish a connection between said driving member and said motor anddisengageable to break said connection, a single manually operablemember and means actuated thereby to shift said driving member from itssaid non-starting position into engagement with the engine, totemporarily disengage said clutch upon said engagement of said drivingmember with the engine and to set said motor into full speed operationwhile said clutch is thus disengaged. 9. A starting device for aninternal combustion engine comprising an electric motor, a .displaceabiepinion out of engagement with the engine in the non-starting positionand bodily movable into said engagement to start the engine, means fordriving said pinion from said motor including a multiple-part clutchautomatically operating to establish a driving connection between saidpinion and said motor and disengageable to break said connection, andmeans tion engine comprising an electric motor, a rotatable memberadapted to be rotatably driven by said motor, said rotatable memberbeing normally out of engagement but movable axially into engagementwith a part of the engine to turn over the latter, a clutch normallyestablishing a driving connection between said rotatable mem loci andsaid motor and operable at will to break and remake the connection,means to energize said motor for low speed operation thereoi and toenergize said motor for high speed opera tion thereof, meansautomatically operating to move said member axially into engagement withsaid engine part when said member is connected through said clutch withsaid motor and the letter is set into low speed rotation; and meansoperable upon said clutch at will when said member is connected to saidengine part to break the connection between said member and said motorwhile retaining said member in connecbetween said member and said motorwhereby the torque of the high speed drive -of said motor may betransmitted through said member to said engine part to turn over thelatter.

11. A starting, device for an internal combus= tion engine comprising anelectric motor operable at low andhigh speeds, a displaceable pinion outof engagement with the engine in the nonstarting position and bodilymovable into said engagement to start the engine, means for driving saidpinion from said motor comprising a multiple-part friction clutchautomatically operating to establish a driving connection between saidpinion and said motor and disengageable to break said connection, meansincluding said motor and said pinion-driving means automaticallyoperating to advance said pinion into engagement with the engine uponactuation of said motor at low speed, a member manually operable totemporarily disengage said clutch after said advancement of said pinioninto engagement with the engine, and means operated by said member indisengaging said clutch to establish an energizing circuit for the fullspeed operation of said motor.

12. A starting device for an internal combustion engine comprising thecombination, with an internal combustion engine having a gear adapted tobe driven to turn over said engine, of an electric motor operable at lowand highspeeds and having an axially movable armature, means 5 forenergizing said motor for low speed rotation and axial movement of saidarmature during said low speed rotation, a rotatable pinion out ofengagement with said engine gear when said armature is in its initialposition but.shiitable i axially into engagement with said engine gearupon said axial movement of said armature. a clutch-controlled drivingconnection between said motor and said pinion automatically operatingupon said low speed rotation and axial move- 15 ment of said armature torotate said pinion idly at the low rotation speed of said motor andadvance said pinion into engagement with said engine gear and therafterupon high speed rotation of said motor to impart the torque of said 20high speed rotation through said pinion to said engine to turnover thelatter, and means comprising a lever operable at will, upon saidadvancement of said pinion into engagement with said engine gear, in onedirection of movement 25 to disengage said clutch and energize saidmotor into high speed rotation and in an opposite direction of movementto re-engage said clutch.

ALBERT CALLSEN.

